The study concerns the survival, regeneration and axonal growth of isolated neuronal groups during development using the tissue culture technique. The organ of Corti of the mouse at different developmental ages will be the tissue of choice. Morphological observations will be made using light microscopy for the study of live tissue; light microscopy and TEM techniques for the study of fixed material. The proposed project includes: 1. Study of the development of the afferent innervation pattern formed by the peripheral fibers of the spiral neurons in the fetal (13th to 18th day of gestation) organ of Corti of the mouse. 2. Ultrastructural study of synaptic profiles in the developing organ of Corti in culture. 3. Study of the growth of the peripheral fibers of the isolated spiral ganglion in culture. BIBLIOGRAPHIC REFERENCES: Scott, G.L., Sobkowicz, H.M., Bereman, B. and Rose, J.E. 1976 Ultrastructure of synaptic profiles in the developing organ of Corti in culture. Neuroscience Abstracts, 1976, vol II: 25. Sobkowicz, H.M., Rose, J.E. and Bereman, B. 1976 Growth patterns of the peripheral axons of the spiral neurons in culture. Abstract in the J. Acoust. Soc. Am. Vol. 60, suppl. No 1, Fall 1976.